Linked Life Data

2547582

Source:http://linkedlifedata.com/resource/pubmed/id/2547582

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1989-9-20
pubmed:abstractText
We reported that TSH and insulin-like growth factor-I (IGF-I), which were known to synergistically stimulate DNA synthesis, synergize to elevate the 1,2-diacylglycerol content of FRTL-5 thyroid cells. We presented evidence that cAMP is the proximal mediator of these actions of TSH. To further define the mechanism of this interaction, we investigated the effects of IGF-I on TSH stimulation of adenylyl cyclase. Long and short term effects of IGF-I or high doses of insulin were studied in FRTL-5 cells that were maintained in serum-, hormone-, and growth factor-free medium for 4-7 days (basal cells). When cells were incubated with high doses of insulin for 7 days and acutely stimulated, a 10-fold increase in sensitivity and a 2-fold increase in maximal responsiveness of cAMP accumulation to TSH were observed. To study shorter term effects, cells were preincubated with insulin for 3 h and then exposed to TSH, cholera toxin, or forskolin. Incubation with high doses of insulin for 3 h caused 30-300% increases in cAMP accumulation at high doses of TSH (greater than or equal to 1 mU/ml), cholera toxin (greater than 0.1 microM), and forskolin, but did not affect the EC50 for TSH. Dose-response studies were consistent with insulin acting via receptors for IGF-I, and IGF-I caused a similar effect. There was a 45% increase in adenylyl cyclase activity stimulated by TSH in membranes isolated from cells incubated with high doses of insulin for 3 h. Pretreatment of FRTL-5 cells with pertussis toxin, which ADP-ribosylates the inhibitory G-protein Gi, or adenosine, which we show inhibits cAMP accumulation by interacting with Gi, did not affect insulin/IGF-I enhancement of cAMP accumulation. We suggest that synergism of actions of TSH and IGF-I may in part be due to IGF-I enhancement of TSH stimulation of adenylyl cyclase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
125
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1315-20
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Insulin-like growth factor-I potentiates thyrotropin stimulation of adenylyl cyclase in FRTL-5 cells.
pubmed:affiliation
Department of Medicine, Cornell University Medical College, New York, New York 10021.
pubmed:publicationType
Journal Article